Telephone receiver



L Patented Oct. 30, 1928;

UNITED srATEs PATENT OFFICE.

WILLIAM F. HENDRY, OF OSSINING, NEW YORK, ASSIGNOR 1O MANHATTAN ELEG- TRICAL SUPPLY COMPANY, INCORPORATED, OF NEW YORK, N. Y., A. CORPORATION or mssacnusn'rrs TELEPHONE RECEIVER.

Application field. July 9, 1924. Serial No. 735,056.

This invention relates to teleplione receivers, and more particularly to new and useful improvements in magnet structures applicable to telephone receivers, loud speakers and the like. I

The object of the present invention is toprovide .a telephone loud speaker of, great efficiency and simplicity, and one which may be easily assembled and adjusted.

With this object in view, I rovide certain arrangements of parts to e disclosed in detail and defined in the claims.

In the drawings, Fig. 1 is atop plan view of a magnet structure and illustrates also a portion of the diaphragm in horizontal crosssection; Fig. 2 is a side elevation of the magnet structure; and Fig. 3 is a vertical crosssection along lines 3-3 of Fig. 2.

Referring now to the drawings, 1 and.2 are U-shaped permanent magnets held between clamping plates 3, 4 and 5, 6, respectively. These plates are clamped against the two sides of the magnet by means of screws 7 and 8, respectively, traversing saidplates. The plates 4 and 5 are mounted on a frame 9 which in turn is fastened to a base drawn b means of a bolt 18 the gaps magnets and traversing the plates. 11 and -1 2.

ormed of plate '11 are 13 and 14 N), and

those formed of plate 12 are 15 an' 16(S).- Pole pieces 13, 15 and 14, 16 are opposite each other. The air .ga between the pole. pieces is determined by a -shaped brass-spacer 17," against the edges of which the legs of mag-' nets 1 and -2 and the plates 11 and 12 are passingthrough I etween the ends of t etwo U-shaped The head of the bolt 18 rests on a washer.19,.

and a nut 20 engaging the screw-threaded end of the bolt.,18, bears against a washer- 21. By

' to an extent determined by. the width of a.

spacer 17.

tightening the bolt '18 the pole Y' ieces 13, 15

. and 14, 16 will be drawn towar each other r An armature 25' is centrally'located within the elliptical space surrounded by the two permanent magnets. The ends of the armature are between the pole pieces 13, 14 and 15,16. The armature 25 is mounted on a resilient wire 26, preferably of hosphor bronze or the like, which is stretche between the two plates 11 and 12. This is accomplished by. means of thumb nuts 27 and 28 engaging the screw-threaded ends of wire 26 and bearing against plates 11 and 12 around slots 29' and 30 cut in said lates and through which the wire 26 passes. he armature is balanced between the pole pieces by the effect of the magnetic fields and also by the resiliency of wire 26 which may be varied by means of nuts 27 and 28. The wire 26 is attached to the armature as near its central point as is feasible, so as to in'suremaximum displacement of the two ends ,of saidarmature in response to the variations in the ma netie flux. These variations in the magnetic flux are generated by voice currents which traverse coils 31 and 32 surrounding the armature 25 on both sides of the wire 26.

The coils 31 and. 32 permit free vibration of the armature and are frictionally held between the plates 11 and 12, suitable insulation in'the form of 'fish paper being provided be-' tween the coils and sa1d plates.

In the present case, the diaphragm is made of paper and. issubstantially in the form of a' double cone 35 mounted in a bracket 36 carried by the frame 9. The magnet structure is provided within this double cone and the operation of-the, armature 25'is transmitted to diaphragm 35 by means of a strut 39 attached to the armature near its point of suspension and between the two coils 31 and 32, the end of 39 being suitably attached by meansof washers and nuts to the cone 35 at its apex. The two coils 3'1 and 32 are connected in series and with the line wires through two bindin posts like37 provided in the base of the i l-shaped s acer 17 and suitably insulated therefrom y means of bushings like'38. It will be understood, of

course, that two terminals like 37 must be provided. Y

The operation of the receiver is as follows. The operating current traversing the coils 31 and 32 will alternately larize the ends of armature 25 N and S. be mature will coils 31 and 32.

While the invention is disclosed as applied to telephone loud speakers of the type in which the diaphragm is exposed and has the shape of a cone or the like, it will be obvious to those skilled in the art that its applica-.

tion to telephone receivers, transmitters or the like, of other types may be readily practiced without departing from the spirit thereof. I

What I claim is: 1. In a telephone receiver, two magnets,

two plates, one contacting with the N and the other with the S poles of said magnets, two pole pieces projecting from each plate, an armature between said pole pieces, a spacer of non-magnetic material, means fordrawing said magnet-poles and said plates together against said spacer, resilient means engaging at least one of said plates for balancing said armature around a pivot point, two-coils surrounding said armature near its center on the two sides of its pivot point, a diaphragm, and a strut having one end attached to said diaphragm and the other end to said armature between said coils.

2. In a telephone receiver, two permanent magnets placed with their like poles opposite each other, two plates,-one contacting with the N and the other with the S poles of said magnets, two pole pieces projecting from one plate towards pole pieces projecting from the other plate, an armature between said polepieces, a spacer of non-mag netic material, means for drawing said magnet poles and said plates together against saidspacer, a resilient wire on which the armature is mounted near its center, means for stretching said wire between said plates,

two coils surrounding said armature near its center on the two sides of its pivot point, a diaphragm, and a strut having one end attached to said diaphra m and the other end to said armature outside of the center point thereof and between said coils.

3. In atelephone receiver, two permanent magnets placed with their like poles opposite each other, the two magnets surrounding a substantially elliptical space, an armature centrally located within said space, two iron plates opposite each other withinsaid space, one contacting with the N and the other with the S poles of said magnets, two pole pieces.

forming partof and projecting from each plate towards the ends of said armature, an

S-shaped spacer of non-magnetic material,

a bolt for drawing said magnet poles and said plates together against said spacer, a resilient phragm, and a strut having one end attached to the apexof said diaphragm and the other end to said armature outside of the center pointthereof but between said coils.

In testimony whereof, I have signed my name to this specification this 7th day of J uly, 192 i.

WILLIAM F. HENDRY.

wire on which the armature is mounted near 4 

